Peak power management for multi-die operations

ABSTRACT

A peak power management (PPM) system is provided for managing peak power operations between two or more NAND memory dies. The PPM system includes a PPM circuit on each NAND memory die. Each PPM circuit includes a first pull-up driver electrically connected to a first power source and a first end of a PPM resistor; a second pull-up driver electrically connected to a second power source and a second end of the PPM resistor; a pull-down driver electrically connected to the second end of the PPM resistor; and a PPM contact pad connected to the second end of the PPM resistor. The PPM contact pads of the two or more NAND memory dies are electrically connected with each other with a common electric potential. The PPM system is configured to manage peak power operations according to the electric potential of the PPM contact pads.

CROSS-REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This application claims priority to PCT/CN2021/075762 filed on Feb. 7,2021, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to the field of semiconductortechnology, and more particularly, to circuit designs and methods forpeak power management in a storage system.

BACKGROUND

In many servers and mobile devices, a NAND storage system is widely usedas the primary non-volatile storage device due to its high storagedensity and relatively low access latency. However, performance of ahigh density storage system, for example, a three-dimensional (3D) NANDstorage system, is often restricted by the maximum amount of power (orpeak current) that it can use. Currently, operations consuming highpower (i.e., peak power operations) that are carried out by variousmemory dies of the NAND storage system can be staggered by a systemcontroller. Only a limited number of peak power operations can beperformed simultaneously. This approach can also result in increasedsystem loading with unnecessary over-management. It is desirable toestablish communications between different memory dies to coordinate thepeak power operations. In the present disclosure, coordination betweentwo or more memory dies can be arranged through a peak power management(PPM) circuit on each memory die, where the PPM contact pads of the PPMcircuits can be held at the same electric potential. Peak poweroperations can be coordinated between two or more memory dies byregulating the electric potential of the PPM contact pads and byimplementing a unique delay time period for each memory die.

BRIEF SUMMARY

One aspect of the present disclosure provides a peak power management(PPM) system for managing peak power operations between two or more NANDmemory dies. The PPM system includes a PPM circuit on each NAND memorydie. Each PPM circuit includes a first pull-up driver electricallyconnected to a first power source and a first end of a PPM resistor; asecond pull-up driver electrically connected to a second power sourceand a second end of the PPM resistor; a pull-down driver electricallyconnected to the second end of the PPM resistor; and a PPM contact padconnected to the second end of the PPM resistor. The PPM contact pads ofthe two or more NAND memory dies are electrically connected with eachother so that an electric potential of the PPM contact pads is commonbetween the two or more NAND memory dies. The PPM system is configuredto manage peak power operations according to the electric potential ofthe PPM contact pads.

In some embodiments, the PPM system further includes a comparator with afirst input terminal electrically connected to the PPM contact pads ofthe two or more NAND memory dies and a second input terminalelectrically connected to a reference voltage.

In some embodiments, the electric potential of the PPM contact pads ishigher than the reference voltage when the pull-down driver is switchedoff.

In some embodiments, the electric potential of the PPM contact pads islower than the reference voltage when the pull-down driver is switchedon.

In some embodiments, the two or more NAND memory dies include a firstNAND memory die and a second NAND memory die, and the PPM contact padheld at an electric potential common between the PPM circuit disposed onthe first NAND memory die and the PPM circuit disposed on the secondNAND memory die.

In some embodiments, the PPM circuit is configured to detect theelectric potential of the PPM contact pad at a first timing during afirst peak power check (PPC) routine for the first NAND memory die;drive the electric potential of the PPM contact pad to a second voltagelevel if the detected electric potential is at a first voltage level atthe first timing, wherein the second voltage level is lower than thefirst voltage level; enable the first NAND memory die to wait for afirst delay time period; determine whether there is a pausing signal inthe electric potential of the PPM contact pad at a second timing duringthe first PPC routine for the first NAND memory die, wherein the secondtiming is later than the first timing; generate the pausing signal inthe electric potential of the PPM contact pad to pause a second PPCroutine for the second NAND memory die if no pausing signal is detectedat the second timing; enable the first NAND memory die to perform afirst peak power operation; and generate a resuming signal in theelectric potential of the PPM contact pad to resume the second PPCroutine for the second NAND memory die after the first NAND memory diecompletes the first peak power operation.

In some embodiments, the PPM circuit is further configured to: detectthe electric potential of the PPM contact pad at a third timing duringthe second PPC routine for the second NAND memory die.

In some embodiments, the PPM circuit is further configured to: enablethe second NAND memory die to pause the second PPC routine if thedetected electric potential is at the second voltage level at the thirdtiming.

In some embodiments, the PPM circuit is further configured to: resumethe second PPC routine for the second NAND memory die in response to theresuming signal generated after the first NAND memory die completes thefirst peak power operation.

In some embodiments, the PPM circuit is further configured to: drive theelectric potential of the PPM contact pad to the second voltage level;and enable the second NAND memory die to wait for a third delay timeperiod, wherein the third delay time period of the second NAND memorydie is different from the first delay time period of the first NANDmemory die.

In some embodiments, the two or more NAND memory dies further include athird NAND memory die, wherein the PPM contact pad is held at anelectric potential common between the PPM circuit disposed on the secondNAND memory die and the PPM circuit disposed on the third NAND memorydie.

In some embodiments, the PPM circuit is further configured to: determinewhether there is the pausing signal in the electric potential of the PPMcontact pad at a fourth timing during the second PPC routine for thesecond NAND memory die, wherein the fourth timing is later than thethird timing; generate the pausing signal in the electric potential ofthe PPM contact pad to pause a third PPC routine for a third NAND memorydie among the multiple NAND memory dies if no pausing signal is detectedat the fourth timing; enable the second NAND memory die to perform asecond peak power operation; and generate the resuming signal in theelectric potential of the PPM contact pad to resume the third PPCroutine for the third NAND memory die after the second NAND memory diecompletes the second peak power operation.

In some embodiments, the PPM circuit is further configured to: enablethe second NAND memory die to wait for a third delay time period if thedetected electric potential is at the first voltage level at the thirdtiming, wherein the third delay time period of the second NAND memorydie is different from the first delay time period of the first NANDmemory die.

In some embodiments, the PPM circuit is further configured to: determinewhether there is the pausing signal in the electric potential of the PPMcontact pad at a fourth timing during the second PPC routine for thesecond NAND memory die, wherein the fourth timing is later than thethird timing.

In some embodiments, the PPM circuit is further configured to: pause thesecond PPC routine for the second NAND memory die if the pausing signalis detected at the fourth timing.

In some embodiments, the PPM circuit is further configured to: resumethe second PPC routine for the second NAND memory die in response to theresuming signal generated after the first NAND memory die completes thefirst peak power operation.

In some embodiments, the first pull-up driver and the second pull-updriver include p-channel metal oxide semiconductor field effecttransistors (MOSFETs).

In some embodiments, the pull-down driver includes an n-channel metaloxide semiconductor field effect transistor (MOSFET).

In some embodiments, the PPM contact pads are electrically connectedthrough a die-to-die connection, comprising a metal interconnect.

In some embodiments, the PPM contact pads are electrically connectedthrough flip-chip bonding, die-to-die bonding, or wire-bonding.

Another aspect of the present disclosure provides a method of peak powermanagement (PPM) for multiple NAND memory dies. The multiple NAND memorydies have a first NAND memory die and a second NAND memory die, and eachof the first NAND memory die and the second NAND memory die includes aPPM circuit having a PPM contact pad held at an electric potentialcommon between the first NAND memory die and the second NAND memory die.The method includes the following steps: detecting the electricpotential of the PPM contact pad at a first timing during a first peakpower check (PPC) routine for the first NAND memory die; driving theelectric potential of the PPM contact pad to a second voltage level ifthe detected electric potential is at a first voltage level at the firsttiming, wherein the second voltage level is lower than the first voltagelevel; enabling the first NAND memory die to wait for a first delay timeperiod; determining whether there is a pausing signal in the electricpotential of the PPM contact pad at a second timing during the first PPCroutine for the first NAND memory die, wherein the second timing islater than the first timing; generating the pausing signal in theelectric potential of the PPM contact pad to pause a second PPC routinefor the second NAND memory die if no pausing signal is detected at thesecond timing; enabling the first NAND memory die to perform a firstpeak power operation; and generating a resuming signal in the electricpotential of the PPM contact pad to resume the second PPC routine forthe second NAND memory die after the first NAND memory die completes thefirst peak power operation.

In some embodiments, the method further includes detecting the electricpotential of the PPM contact pad at a third timing during the second PPCroutine for the second NAND memory die.

In some embodiments, the method further includes enabling the secondNAND memory die to pause the second PPC routine if the detected electricpotential is at the second voltage level at the third timing.

In some embodiments, the method further includes resuming the second PPCroutine for the second NAND memory die in response to the resumingsignal generated after the first NAND memory die completes the firstpeak power operation.

In some embodiments, the resuming the second PPC routine for the secondNAND memory die includes driving the electric potential of the PPMcontact pad to the second voltage level; and enabling the second NANDmemory die to wait for a third delay time period, wherein the thirddelay time period of the second NAND memory die is different from thefirst delay time period of the first NAND memory die.

In some embodiments, the resuming the second PPC routine for the secondNAND memory die further includes determining whether there is thepausing signal in the electric potential of the PPM contact pad at afourth timing during the second PPC routine for the second NAND memorydie, wherein the fourth timing is later than the third timing; andgenerating the pausing signal in the electric potential of the PPMcontact pad to pause a third PPC routine for a third NAND memory dieamong the multiple NAND memory dies if no pausing signal is detected atthe fourth timing.

In some embodiments, the resuming the second PPC routine for the secondNAND memory die further includes enabling the second NAND memory die toperform a second peak power operation; and generating the resumingsignal in the electric potential of the PPM contact pad to resume thethird PPC routine for the third NAND memory die after the second NANDmemory die completes the second peak power operation.

In some embodiments, the method further includes enabling the secondNAND memory die to wait for a third delay time period if the detectedelectric potential is at the first voltage level at the third timing,wherein the third delay time period of the second NAND memory die isdifferent from the first delay time period of the first NAND memory die.

In some embodiments, the method further includes determining whetherthere is the pausing signal in the electric potential of the PPM contactpad at a fourth timing during the second PPC routine for the second NANDmemory die, wherein the fourth timing is later than the third timing.

In some embodiments, the method further includes pausing the second PPCroutine for the second NAND memory die if the pausing signal is detectedat the fourth timing.

In some embodiments, the method further includes resuming the second PPCroutine for the second NAND memory die in response to the resumingsignal generated after the first NAND memory die completes the firstpeak power operation.

In some embodiments, the method further includes prior to performing thefirst peak power operation, waiting for a second delay time period inthe first PPC routine for the first NAND memory die.

In some embodiments, the generating the resuming signal includes drivingthe electric potential of the PPM contact pad to the first voltagelevel.

In some embodiments, the generating the pausing signal includesgenerating a positive pulse in the electric potential of the PPM contactpad, the positive pulse having a pulse width in a range between about0.1 μS and about 10 μS.

In some embodiments, the determining whether there is the pausing signalcomprises measuring the electric potential of the PPM contact pad at afirst probing and a second probing, wherein the first probing and thesecond probing are separated with a measurement time period longer thanthe pulse width.

Other aspects of the present disclosure can be understood by thoseskilled in the art in light of the description, the claims, and thedrawings of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present disclosureand, together with the description, further serve to explain theprinciples of the present disclosure and to enable a person skilled inthe pertinent art to make and use the present disclosure.

FIG. 1A illustrates a storage system with one or more memory chips,according to some embodiments of the present disclosure.

FIG. 1B illustrates a top-down view of a memory die, according to someembodiments of the present disclosure.

FIG. 2A illustrates a peak power management system in a memory chip,according to some embodiments of the present disclosure.

FIG. 2B illustrates another peak power management system in a memorychip, according to some embodiments of the present disclosure.

FIG. 3 illustrates a peak power management circuit, according to someembodiments of the present disclosure.

FIG. 4 illustrates a peak power check routine, according to someembodiments of the present disclosure.

FIGS. 5-7 illustrate implementations of the peak power check routineshown in FIG. 4 on two memory dies, according to some embodiments of thepresent disclosure.

FIG. 8 illustrates a measurement scheme for a pausing signal, accordingto some embodiments of the present disclosure.

FIGS. 9-10 illustrate implementations of the peak power check routineshown in FIG. 4 on three memory dies, according to some embodiments ofthe present disclosure.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

Embodiments of the present disclosure will be described with referenceto the accompanying drawings.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, itshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present disclosure. It will be apparent to aperson skilled in the pertinent art that the present disclosure can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described can include a particular feature,structure, or characteristic, but every embodiment can not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to affect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology can be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, can be used to describe any feature,structure, or characteristic in a singular sense or can be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, canbe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context. In addition, the term “basedon” can be understood as not necessarily intended to convey an exclusiveset of factors and may, instead, allow for existence of additionalfactors not necessarily expressly described, again, depending at leastin part on context.

As used herein, the term “nominal/nominally” refers to a desired, ortarget, value of a characteristic or parameter for a component or aprocess step, set during the design phase of a product or a process,together with a range of values above and/or below the desired value.The range of values can be due to slight variations in manufacturingprocesses or tolerances. As used herein, the term “about” indicates thevalue of a given quantity that can vary based on a particular technologynode associated with the subject semiconductor device. Based on theparticular technology node, the term “about” can indicate a value of agiven quantity that varies within, for example, 10-30% of the value(e.g., ±10%, ±20%, or 30% of the value).

FIG. 1A illustrates a storage system 10, according to some embodimentsof the present disclosure. The storage system 10 (also referred to as aNAND storage system or a solid state drive) can include a hostcontroller 20 and one or more memory chips 25-1, 25-2, 25-3, . . . ,25-n. Each semiconductor memory chip 25 (hereafter just “memory chip”)can be a NAND chip (i.e., “flash,” “NAND flash” or “NAND”). The solidstate drive (SSD) 10 can communicate with a host computer 15 through thehost controller 20, where the host controller 20 can be connected to theone or more memory chips 25-1, 25-2, 25-3, . . . , 25-n, via one or morememory channels 30-1, 30-2, 30-3, . . . , 30-n. In some embodiments,each memory chip 25 can be managed by the host controller 20 via amemory channel 30.

The host computer 15 sends data to be stored at the NAND storage systemor SSD 10 or retrieves data by reading the SSD 10. The host controller20 can handle I/O requests received from the host computer 15, ensuredata integrity and efficient storage, and manage the memory chip 25. Thememory channels 30 can provide data and control communication betweenthe host controller 20 and each memory chip 25 via a data bus. The hostcontroller 20 can select one of the memory chip 25 according to a chipenable signal.

FIG. 1B illustrates a top-down view of a NAND flash memory 100,according to some embodiments of the present disclosure. The NAND flashmemory 100 can be a memory die (or a die) or any portion of a memorydie. In some embodiments, each memory chip 25 in FIG. 1A can include oneor more memory dies, e.g., one or more NAND flash memories 100. In someembodiments, each NAND flash memory 100 can include one or more memoryplanes 101, each of which can include a plurality of memory blocks 103.Identical and concurrent operations can take place at each memory plane101. The memory block 103, which can be megabytes (MB) in size, is thesmallest size to carry out erase operations. Shown in FIG. 1B, theexemplary NAND flash memory 100 includes four memory planes 101 and eachmemory plane 101 includes six memory blocks 103. Each memory block 103can include a plurality of memory cells, where each memory cell can beaddressed through interconnections such as bit lines and word lines. Thebit lines and word lines can be laid out perpendicularly (e.g., in rowsand columns, respectively), forming an array of metal lines. Thedirection of bit lines and word lines are labeled as “BL” and “WL” inFIG. 1B. In this disclosure, the memory block 103 is also referred to asthe “memory array” or “array.” The memory array is the core area on amemory die, performing storage functions.

The NAND flash memory 100 also includes a periphery region 105, an areasurrounding memory planes 101. The periphery region 105 contains manydigital, analog, and/or mixed-signal circuits to support functions ofthe memory array, for example, page buffers 50, row decoders 40, columndecoders 60, peripheral circuits 70 and sense amplifiers 80. Peripheralcircuits 70 include active and/or passive semiconductor devices, such astransistors, diodes, capacitors, resistors, etc., as would be apparentto a person of ordinary skill in the art.

It is noted that the layout of the electronic components in the SSD 10and the NAND flash memory 100 in FIGS. 1A and 1B are shown as examples.The SSD 10 and the NAND flash memory 100 can have other layout and caninclude additional components. For example, the NAND flash memory 100can also have high-voltage charge pumps, I/O circuits, etc. The SSD 10can also include firmware, data scrambler, etc.

FIG. 2A illustrates a peak power management system 200A of the memorychip 25, according to some embodiments of the present disclosure. Thepeak power management (PPM) system 200A can be implemented in eachmemory chip 25 of the NAND storage system 10 in FIG. 1A, where eachmemory chip 25 can include a plurality of memory dies 100-1, 100-2, . .. , 100-(n−1), 100-n, and each memory die can be similar to the NANDflash memory 100 discussed previously in reference with FIG. 1B. In someembodiments, each NAND flash memory 100 can include a peak powermanagement (PPM) circuit 202 (e.g., 202-1, 202-2, . . . , 202-(n−1),202-n), where each PPM circuit 202 can include a PPM contact pad 204(also referred to as PPM pin). The PPM circuits 202-1, 202-2, . . . ,202-(n−1), 202-n on different NAND flash memories 100-1, 100-2, . . . ,100-(n−1), 100-n of the memory chip 25 can communicate with each otherthrough the PPM contact pads 204 (e.g., 204-1, 204-2, . . . , 204-(n−1),204-n). In some embodiments, the PPM contact pads 204 between two NANDflash memories 100 can be electrically connected with each other througha plurality of die-to-die connections 205. For example, the PPM contactpad 204-1 on the NAND flash memory 100-1 can be electrically connectedwith the PPM contact pad 204-2 on the NAND flash memory 100-2 throughthe die-to-die connection 205. The PPM contact pad 204-(n−1) on the NANDflash memory 100-(n−1) can also be electrically connected with the PPMcontact pad 204-n on the NAND flash memory 100-n through the die-to-dieconnection 205. In some embodiments, the die-to-die connection 205 canbe a metal interconnect formed by wire-bonding. In some embodiments, themetal interconnect can be a metal wire or any suitable metal orconductive material formed by flip-chip bonding or die-to-die bonding.In some embodiments, the metal interconnect can be formed by athrough-silicon VIA (e.g., a through-array structure).

By using the die-to-die connections 205 described above, communicationsbetween two different memory dies (e.g., between NAND flash memories100-1 and 100-2) can be established as a PPM group 203 in the PPM system200A. As such, the NAND storage system 10 can send operation commands tothe memory chip 25, where at any time the NAND storage system 10 cancontrol the system's power consumption through the PPM circuit 202 byselecting one of the two memory dies in the PPM group 203.

FIG. 2B illustrates a PPM system 200B, according to some embodiments ofthe present disclosure. Similar to the PPM system 200A, the PPM system200B can also be implemented in each memory chip 25 of the NAND storagesystem 10 in FIG. 1A, where each memory die (e.g., NAND flash memory100) includes one PPM circuit 202 (e.g., 202-1, 202-2, 202-3, . . . ,202-n). Each PPM circuit 202 includes the PPM contact pad 204 (e.g.,204-1, 204-2, 204-3, . . . , 204-n), through which the PPM circuits 202on different NAND flash memories 100 can communicate with each other. Insome embodiments, the PPM contact pads 204 between the NAND flashmemories 100 can be electrically connected with each other through aplurality of die-to-die connections 205. For example, the PPM contactpad 204-1 on the NAND flash memory 100-1 can be electrically connectedwith the PPM contact pad 204-2 on the NAND flash memory 100-2 throughthe die-to-die connection 205, while the PPM contact pad 204-2 on theNAND flash memory 100-2 can be electrically connected with the PPMcontact pad 204-3 on the NAND flash memory 100-3 through anotherdie-to-die connection 205. As such, the PPM contact pads 204 for theentire PPM system 200B can be electrically connected through thedie-to-die connection 205. In the other words, the PPM system 200B canbe considered as one PPM group 203. Communications between differentmemory dies on the same memory chip can thereby be established throughthe PPM system 200B. The NAND storage system 10 can send operationcommands to the memory chip 25, where at any time the NAND storagesystem 10 can control the system's power consumption through the PPMcircuits 202 by selecting one of the memory dies.

FIG. 3 illustrates an exemplary PPM circuit 202 on the NAND flash memory100, according to some embodiments of the present disclosure. The PPMcircuit 202 can include a first pull-up driver 314, where one terminalof the first pull-up driver 314 is connected to a first power source 312with a first voltage V_(dd_1). In some embodiments, the first pull-updriver 314 can be a metal-oxide-semiconductor-field-effect-transistor(MOSFET). In some embodiments, the first pull-up driver 314 can be ap-channel MOSFET (i.e., pFET), where a source terminal of the firstpull-up driver 314 can be connected to the first power source 312 and adrain terminal of the first pull-up driver 314 can be connected to afirst end of a PPM resistor 318 with a resistance R_(ppm).

In some embodiments, the PPM circuit 202 can also include a secondpull-up driver 315, where one terminal of the second pull-up driver 315is connected to a second power source 313 with a second voltageV_(dd_2). In some embodiments, the second pull-up driver 315 can be ametal-oxide-semiconductor-field-effect-transistor (MOSFET). In someembodiments, the second pull-up driver 315 can be a p-channel MOSFET(i.e., pFET), where a source terminal of the second pull-up driver 315can be connected to the second power source 313 and a drain terminal ofthe second pull-up driver 315 can also be connected to a second end ofthe PPM resistor 318. In this configuration, the first pull-up driver314 and the second pull-up driver 315 are connected in parallel.

In some embodiments, the first pull-up driver 314 can have a firstcurrent I_(up_1); and the second pull-up driver 315 can have a secondcurrent I_(up_2). Current flowing through the first pull-up driver 314and the second pull-up driver 315 can be controlled by applying a biason a gate terminal 316 of the first pull-up driver and/or a gateterminal 317 of the second pull-up driver 315. In one example, the firstpull-up driver 314 can be kept as slightly or weakly turned on (e.g.,with low trans-conductance), and thereby also referred to as the “weakpull-up driver.” In some embodiments, the second pull-up driver 315 canbe fully switched on (e.g., with high trans-conductance), and therebyalso referred to as the “strong pull-up driver.” The first currentI_(up_1) can be much less than the second current I_(up_2). In someembodiments, the first current I_(up_1) can be in a range between about100 nA to about 1 μA. In some embodiments, the second current I_(up_2)can be in a range between about 10 μA to 1 mA. In some embodiments, thefirst voltage V_(dd_1) and the second voltage V_(dd_2) can have the samemagnitude.

In some embodiments, the PPM circuit 202 also includes a pull-downdriver 336. In some embodiments, the pull-down driver 336 can be aMOSFET. In some embodiments, the pull-down driver 336 can be ann-channel MOSFET (i.e., nFET). A source terminal of the pull-down driver336 can be grounded, and a drain terminal of the pull-down driver 336can be connected to the second end of the PPM resistor 318 at a node322.

In some embodiments, the second end of the PPM resistor 318, the drainterminal of the second pull-up driver 315 and the drain terminal of thepull-down driver 336 are also electrically connected to the PPM contactpad 204 at the node 322. For the PPM system 200A having two PPM circuits202 in each PPM group 203 (as shown in FIG. 2A), the PPM contact pads204 in the same PPM group 203 can be held to an electrical potentialV_(ppm) at the node 322, common to the two PPM contact pads 204 and thetwo PPM circuits 202, because the two PPM contact pads 204 areelectrically connected through the die-to-die connection 205 (see FIG.2A). For the PPM system 200B having two or more PPM circuits 202 in eachPPM group 203 (as shown in FIG. 2B), the PPM contact pads 204 in thesame PPM 203 can also be held to the electrical potential V_(ppm) at thenode 322, common to all the PPM contact pads 204 and the PPM circuits202 in the PPM system 200B, because all the PPM contact pads 204 areelectrically connected through the die-to-die connections 205 (see FIG.2B).

In some embodiments, the PPM circuit 202 can also include a comparator328, with a first input terminal 324 at a reference voltage V_(ref) anda second input terminal 326 connected to the node 322 (or the PPMcontact pad 204). The comparator 328 can be an operational amplifierused for comparing an input voltage V_(in) at the second input terminal326 with the reference voltage V_(ref) at the first input terminal 324,where an output voltage Vout at an output terminal 330 can indicatewhether the input voltage V_(in) is above or below the reference voltageV_(ref). For example, the output voltage Vout can be a positive voltagewhen the input voltage V_(in) is larger than the reference voltageV_(ref). On the other hand, the output voltage Vout can be a negativevoltage when the input voltage V_(in) is smaller than the referencevoltage V_(ref).

In some embodiments, the PPM circuit 202 can further include an inverter332 with an input terminal connected to the output terminal 330 of thecomparator 328. The inverter 332 can invert an input signal. Forexample, when the output voltage Vout of the comparator 328 is apositive voltage, a PPM enablement signal enPPM generated by theinverter 332 at an output terminal 334 can be zero, i.e., the PPMenablement signal enPPM=0. On the other hand, when the output voltageVout of the comparator 328 is a negative voltage, the PPM enablementsignal enPPM=1. In the other words, when the electrical potentialV_(ppm) at the node 322 is larger (or higher) than the reference voltageV_(ref) (i.e., V_(ppm)>V_(ref)), the PPM enablement signal enPPM=0. Whenthe electrical potential V_(ppm) at the node 322 is smaller (or lower)than the reference voltage V_(ref)(i.e., V_(ppm)<V_(ref)), the PPMenablement signal enPPM=1.

In some embodiments, there can be an optional RC filter 344 connectedbetween the node 322 and the second input terminal 326 of the comparator328. The RC filter 344 can be used to filter out unwanted signals withina certain frequency range.

As discussed previously, the PPM contact pads 204 in the same PPM group203 can be electrically connected for the PPM system 200A (in FIG. 2A)and the PPM system 200B (in FIG. 2B), i.e., the PPM contact pads 204 ofthe same PPM group 203 can be held at the electric potential V_(ppm),common to all the PPM contact pads 204 in the same PPM group 203.Therefore, each PPM group 203 only needs one comparator 328 that iselectrically connected to one of the PPM contact pads 204 at the node322. And the PPM enablement signal enPPM indicates the electricalpotential V_(ppm) for the two or more memory dies in the PPM group 203.

Referring to FIG. 3, during operation, a first control signal 340 can besent to the gate terminal 317 of the second pull-up driver 315 to switchthe second pull-up driver 315 on or off. For example, if the firstcontrol signal 340 has a voltage less than a threshold voltage of thesecond pull-up driver 315, the second pull-up driver 315 can be switchedon, and the second current I_(up_2) can thereby flow through the secondpull-up driver 315. If the first control signal 340 has a voltage higherthan the threshold voltage of the second pull-up driver 315, the secondpull-up driver 315 can be switched off.

The current flowing through the pull-down driver 336 is also referred toas a pull-down current I_(pull_dn). In the configuration of FIG. 3, thepull-down current I_(pull_dn) can be the sum of the first currentI_(up_1) and the second current I_(up_2). When the second pull-up driver315 is switched on, the pull-down current I_(pull_dn) is dominated bythe second current I_(up_2) because the second current I_(up_2) flowingthrough the “strong pull-up driver” is much larger than the firstcurrent I_(up_1) flowing through the “weak pull-up driver,” as discussedpreviously. When the second pull-up driver 315 is switched off, only thefirst current I_(up_1) flows through the PPM resistor 318 and the node322 to the pull-down driver 336.

When a second control signal 342 is sent to a gate terminal 338 of thepull-down driver 336, the pull-down driver 336 can be switched on oroff. For example, if the second control signal 342 has a voltage higherthan a threshold voltage of the pull-down driver 336, the pull-downdriver 336 can be switched on, and a conductive path can be formed fromthe node 322 to the ground. If the second control signal 342 has avoltage less than the threshold voltage of the pull-down driver 336, thepull-down driver 336 can be switched off.

In some embodiments, the pull-down driver 336 can be operated as acurrent controller. In this example, when the pull-down driver 336 isswitched on, the magnitude of the current flowing through the pull-downdriver 336 from the node 322 to the ground (i.e., the pull-down currentI_(pull_dn)) depends on the second control signal 342. When thepull-down driver 336 is an nFET, as shown in FIG. 3, the pull-downcurrent I_(pull_dn) can be determined by the voltage level of the secondcontrol signal 342 and the trans-conductance of the pull-down driver336. According to some embodiments of the present disclosure, a currentprofile I_(cc) of a memory die (e.g., the NAND flash memory 100-1) cancorrespond to the voltage level of the second control signal 342, andthereby correspond to the pull-down current I_(pull_dn). Therefore, thepull-down current I_(pull_dn) can function as a current mirror of thecurrent profile I_(cc) of the memory die.

In some embodiments, the pull-down current I_(pull_dn) can beproportional to a current level of the current profile I_(cc). Thepull-down current I_(pull_dn) can be scaled down proportionally from thecurrent profile I_(cc). For example, if the memory die is operating with200 mA of current, the pull-down current I_(pull_dn) of the PPM circuit202 can be 200 μA. Therefore, memory operations and correspondingcurrent can be regulated for each memory die through the pull-downcurrent I_(pull_dn). Furthermore, through the die-to-die connections atthe PPM contact pads, peak power operations in the PPM group 203 can becoordinated between two or more memory dies as shown in FIGS. 2A and 2B.

For example, when the PPM circuit 202 is at a reset state, the secondpull-up driver 315 can be switched off and no second current I_(up_2)flows through the node 322. In the meantime, the first pull-up driver314 can be kept on by default, and the pull-down driver 336 can beswitched off. Accordingly, the electric potential V_(ppm) at node 322(or at PPM contact pad 204) can be held at a first voltage level, higherthan the reference voltage V_(ref), via a conductive path through thePPM resistor 318 and the first pull-up driver 314 to the first powersource 312.

In some embodiments, at the reset state, the pull-down driver 336 canalso be kept on slightly or weakly (e.g., with low trans-conductance)such that the electrical potential of V_(ppm) can be held close to thefirst voltage level, still higher than the reference voltage V_(ref). Inthis example, the pull-down current I_(pull_dn) can be determined by thefirst current I_(up_1) in the absent of the second current I_(up_2).This low level of pull-down current I_(pull_dn) corresponds to a lowlevel current I_(L) running on the memory die. The memory die canperform operations that consume the low level current I_(L).

In some embodiments, the pull-down driver 336 can be fully switched on(e.g., with high trans-conductance). In this example, the electricpotential V_(ppm) at node 322 (or PPM contact pad 204) can be held at asecond voltage level, lower than the reference voltage V_(ref), viaanother conductive path through the pull-down driver 336 to the ground.

In some embodiments, a positive pulse in the electric potential V_(ppm)can be formed by switching on the second pull-up driver 315 andsubsequently (e.g., about 1 s later), switching on the pull-down driver336.

As discussed previously, when the second pull-up driver 315 is switchedon, the pull-down current I_(pull_dn) can be the sum of the firstcurrent I_(up_1) and the second current I_(up_2). This high level ofpull-down current I_(pull_dn) corresponds to a high level current I_(H)running on the memory die. The memory die can perform a peak poweroperation (PPO) that consume the high level current I_(H).

FIG. 4 illustrates a peak power check routine 400 associated with thepeak power management system 200A in FIG. 2A or 200B in FIG. 2B usingthe PPM circuit 202 in FIG. 3, according to some embodiments of thepresent disclosure. It should be understood that the peak power check(PPC) routine 400 is not exhaustive and that other operation steps canbe performed as well before, after, or between any of the illustratedoperation steps. In some embodiments, some operation steps of the PPCroutine 400 can be omitted or other operation steps can be included,which are not described here for simplicity. In some embodiments,operation steps of the PPC routine 400 can be performed in a differentorder and/or vary.

The PPC routine 400 provides an exemplary method of managing peak poweroperations in the PPM group 203 with two or more memory dies, where eachmemory die includes at least one PPM circuit 202. The example below isshown for a particular memory die, where its peak power operation is notperformed simultaneously with another peak power operation on anothermemory die in the same PPM group 203. As such, the total power (orcurrent) consumed by the PPM group 203 can be regulated and controlledto below a predetermined value.

As shown in FIG. 4, the PPC routine 400 starts at operation step S405,where the PPM circuit 202 on the particular memory die is at the resetstate. As discussed previously with reference to FIG. 3, at the resetstate, the pull-down driver 336 of the PPM circuit 202 can be switchedoff.

When the particular memory die is about to perform the peak poweroperation, the PPC routine 400 can be launched for the particular memorydie and can proceed to operation step S410, a first check point in thePPC routine 400. At operation step S410, the electric potential V_(ppm)of the PPM contact pad 204 is first detected and then compared with thereference voltage V_(ref).

If it is determined that the electric potential V_(ppm) is larger orhigher than the reference voltage V_(ref), i.e., at the first voltagelevel (also referred to as the “high” level), the PPC routine canproceed to operation step S415. As discussed previously, the electricpotential V_(ppm) is common to all the PPM contact pads 204 of the PPMcircuit 202 in the same PPM group 203. When the electric potentialV_(ppm) is at the first voltage level, it indicates that none of thememory die in the same PPM 203 is performing the peak power operation.As such, the particular memory die can continue its PPC routine 400.

To prevent other memory dies in the same PPM group 203 performing thepeak power operations and to reserve the power/current budget for theparticular memory die, at operation step S415, the electric potentialV_(ppm) of the PPM contact pad 204 can be driven to the second voltagelevel that is smaller or lower than the reference voltage V_(ref). Theelectric potential V_(ppm) can be set at the second voltage level (alsoreferred to as the “low” level) by switching on the pull-down driver 336of the PPM circuit 202 on the particular memory die.

The PPC routine 400 then proceeds to operation step S420, where theparticular memory die is enabled to wait for a first delay time periodt_(dly_1). In some embodiments, the first delay time period t_(dly_1) isunique to the particular memory die in the PPM group 203. In the otherwords, each memory die in the PPM group 203 has a different first delaytime period t_(dly_1). For example, the NAND flash memory 100-1 and theNAND flash memory 100-2 in FIG. 2A have the first delay time periodst_(dly_1) with different values. In case that any other memory die andthe particular memory die launch the PPC routines 400 and start thefirst check point (i.e., operation step S410) at the same time, due todifferent first delay time periods t_(dly_1), the PPC routines 400 forthe other memory die and the particular memory die do not proceed tooperation step S425 (i.e., a second check point) simultaneously. Assuch, memory dies in the same PPM group 203 can be de-synchronized whenthey perform PPOs.

The PPC routine 400 then proceeds to operation step S425, the secondcheck point, where it is determined whether there is a pausing signal inthe electric potential V_(ppm) of the PPM contact pad 204. In someembodiments, the pausing signal includes a positive pulse of theelectric potential V_(ppm).

If no pausing signal is detected, the PPC routine 400 continues tooperation step S430, where the pausing signal can be generated. In theexample that the pausing signal includes the positive pulse in theelectric potential V_(ppm), the pausing signal can be generated byswitching on the second pull-up driver 315 and then (e.g., about 1 slater) switching on the pull-down driver 336. The pausing signal isgenerated such that other PPC routines for other memory dies in the PPMgroup 203 can be paused according to the pausing signal.

At operation step S435, the PPC routine 400 waits for a second delaytime period t_(ppm). In some embodiments, the second delay time periodt_(ppm) can be different for the two or more memory dies in the same PPMgroup 203. Different from the first delay time period t_(dly_1), in someembodiments, the second delay time period t_(ppm) can be the same forthe two or more memory dies in the same PPM group 203. The second delaytime period t_(ppm) can be any suitable time period predetermined by theNAND storage system 10 to include communication delays between the PPCroutine 400 and the PPO. In some embodiments, the second delay timeperiod t_(ppm) depends on firmware design for the NAND storage system10.

When the PPC routine 400 starts operation step S440, the particularmemory die can start to perform the PPO, where the high current levelI_(H) on the particular memory die can correspond to the pull-downcurrent I_(pull_dn) flowing through the pull-down driver 336 of the PPMcircuit 202, which is a sum of the first current I_(up_1) and the secondcurrent I_(up_2).

After the particular memory die completes the PPO, the PPC routine 400proceeds to operation step S445, where a resuming signal can begenerated in the electric potential V_(ppm) of the PPM contact pad 204.The resuming signal can be used for other memory dies to resume theirPPC routines that are in pause. In some embodiments, the resuming signalcan be generated by driving the electric potential V_(ppm) to the firstvoltage level (e.g., from the low level to the high level). For example,the second pull-up driver 315 of the PPM circuit 202 on the particularmemory die can be switched off. The pull-down driver 336 can also beswitched off. In some embodiments, the pull-down driver 336 can be kepton slightly or weakly such that the pull-down current I_(pull_dn) isabout the same as the first current I_(up_1), which corresponds to thelow current level I_(L) used by operations on the memory die.

If at operation step S410 the electric potential V_(ppm) is determinedto be smaller or lower than the reference voltage V_(ref), i.e., at thesecond voltage level, it indicates that at least one of the other memorydies of the PPM group 203 is performing PPO or is about to perform PPOand has driven the electric potential V_(ppm) from the high level to thelow level. Then the PPC routine 400 for the particular memory die ispaused at operation step S450.

Similarly, if the pausing signal is detected at operation step S425, thePPC routine 400 for the particular memory die also pauses at operationstep S450. In some embodiments, the PPC routine 400 constantly checkswhether there is the pausing signal while waiting at operation step S420during the first delay time period t_(dly_1). In this example, thepausing signal can trigger the PPC routine 400 to pause at operationstep S450 as soon as the pausing signal is detected during the firstdelay time period t_(dly_1) at operation step S420.

When the PPC routine 400 for the particular memory die is paused atoperation step S450, it constantly checks if there is the resumingsignal in the electric potential V_(ppm) of the PPM contact pad 204. Inthe example that the resuming signal is generated by driving theelectric potential V_(ppm) to the first voltage level, i.e., from thelow level to the high level, a rising edge of the electric potentialV_(ppm) can be used to trigger the PPC routine 400, which is paused atoperation step S450, to resume. If the resuming signal is detected atoperation step S455, the PPC routine 400 continues to operation stepS460, where the electric potential V_(ppm) is driven to the secondvoltage level (i.e., the low level) to reserve the power/currentresource for the particular memory die. The PPC routine 400 remainspaused at operation step S450 if there is no resuming signal detected.

Next, the PPC routine 400 proceeds to operation step S420. In someembodiments, the PPC routine 400 can proceed to operation step S435,when there are only two memory dies in one PPM group. In this example,waiting for the first delay time period t_(dly_1) can be skipped for theparticular memory die after resuming the PPC routine 400 because theother memory die has completed PPO. Thus, there is no coincidence thatthe two memory dies perform PPO simultaneously after pause-resume.

FIGS. 5-7 illustrate three exemplary implementations of the PPC routine400 for the PPM system 200A in FIG. 2A, where each PPM group 203includes two memory dies, e.g., “Die 0” (also referred to as a firstNAND memory die) and “Die 1” (also referred to as a second NAND memorydie). Die 0 and Die 1 can be similar to the NAND flash memory 100 shownin FIGS. 1-2.

In the example shown in FIG. 5, the two memory dies, Die 0 and Die 1,are all at the reset state at the beginning of the time sequence. Die 0receives a command signal to perform a first PPO before Die 1 receivesits command signal to perform a second PPO. Therefore, a first PPCroutine 400 _(Die_0) is launched first for Die 0. At time t₁ (i.e., afirst timing), the first PPC routine 400 _(Die_0) for Die 0 startsoperation step S410 to detect the electric potential V_(ppm) of the PPMcontact pad 204 of the PPM circuit 202 on Die 0. Because neither Die 0or Die 1 is performing the first PPO or the second PPO, the electricpotential V_(ppm) is held at the high level (the first voltage level)with the pull-down current I_(pull_dn) of a magnitude negligible orabout the first current I_(up_1) on both Die 0 and Die 1. Namely, bothDie 0 and Die 1 are performing operations with the low current levelI_(L).

After determining the electric potential V_(ppm) is at the high level attime t₁, the electric potential V_(ppm) is driven to the low level(i.e., the second voltage level) according to operation step S415 of thefirst PPC routine 400 _(Die_0) for Die 0.

When Die 1 receives its command signal to perform the PPO, a second PPCroutine 400 _(Die_1) can be launched for Die 1 and proceeds to operationstep S410 at time t₂ (i.e., a third timing). In this example, the timet₂ is later than the time t₁. Since the electric potential V_(ppm) hasbeen driven to the low level according to the first PPC routine 400_(Die_0) for Die 0, the second PPC routine 400 _(Die_1) for Die 1 ispaused at operation step S450.

After driving the electric potential V_(ppm) to the low level, the firstPPC routine 400 _(Die_0) enables Die 0 to wait for the first delay timeperiod t_(dly_1_Die 0) at operation step S420. Because no pausing signal(e.g., the positive pulse of the electric potential V_(ppm)) is detectedat operation step S425, the pausing signal is generated according tooperation step S430 of the first PPC routine 400 _(Die_0) for Die 0 attime t₃ (i.e., a second timing). After waiting for the second delay timeperiod t_(ppm) (operation step S435), Die 0 can start the first PPO attime t₄ according to operation step S440 of the first PPC routine 400_(Die_0). At time t₅, Die 0 completes the first PPO and the resumingsignal is generated according to operation step S445 of the first PPCroutine 400 _(Die_0). In this example, the resuming signal is generatedby driving the electric potential V_(ppm) to the high level.

Between time t₂ and time t₅, the second PPC routine 400 _(Die_1) for Die1 is paused at operation step S450. When the resuming signal is detectedin the electric potential V_(ppm) at time t₅, the second PPC routine 400_(Die_1) for Die 1 resumes. In this example, the rising edge of theelectric potential V_(ppm) at time t₅ can be used to trigger the secondPPC routine 400 _(Die_1) to resume. The electric potential V_(ppm) issubsequently driven to the low level at time t₆ according to operationstep S460 of the second PPC routine 400 _(Die_1). In FIG. 5, a fallingedge of the electric potential V_(ppm) is thereby generated. It is notedthat a duration between the rising edge generated according to the firstPPC routine 400 _(Die_0) for Die 0 at time t₅ and the falling edgegenerated according to the second PPC routine 400 _(Die_1) for Die 1 attime t₆ is longer than a pulse width of the positive pulse generatedaccording to the first PPC routine 400 _(Die_0) for Die 0 at time t₃. Bydriving the electric potential V_(ppm) to the low level, thepower/current resource can be reserved for Die 1. For example, in caseanother PPO is requested for Die 0, the new PPC routine will be pausedafter the first check point (at operation step S410). As such, thesecond PPC routine 400 _(Die_1) for Die 1, which has been paused atoperation step S450, can finish without further delay.

Next, the second PPC routine 400 _(Die_1) for Die 1 proceeds tooperation step S420, where Die 1 waits for the first delay time periodt_(dly_1_Die 1). At operation step S425 of the second PPC routine 400_(Die_1), it is checked whether there is the pausing signal in theelectric potential V_(ppm). The pausing signal (e.g., the positive pulseof the electric potential V_(ppm)) is generated at time t₇ (alsoreferred to as a fourth timing) when it is not detected. After waitingfor the second delay time period t_(ppm) at operation step S435, Die 1starts to perform the second PPO at operation step S440 according tosecond PPC routine 400 _(Die_1). At time t₅, Die 1 completes the secondPPO and the resuming signal is generated by driving the electricpotential V_(ppm) to the high level at operation step S445.

As such, Die 0 and Die 1 complete the first PPO and the second PPO,respectively. By using the first PPC routine 400 _(Die_0) and the secondPPC routine 400 _(Die_1), two memory dies (e.g., Die 0 and Die 1) in thesame PPM group 203 (see FIG. 2) can coordinate their PPOs through thePPM circuits 202. By regulating the electric potential V_(ppm) shared bythe PPM contact pads 204, PPOs can be de-synchronized for the two memorydies.

FIG. 6 illustrates another exemplary implementation of the PPC routine400, according to some embodiments of the present disclosure. In FIG. 6,Die 0 (i.e., the first NAND memory die) and Die 1 (i.e., the second NANDmemory die) receive the command signals for the first PPO and the secondPPO simultaneously from the NAND storage system 10. Therefore, the firstPPC routine 400 _(Die_0) and the second PPC routine 400 _(Die_1) arriveat the first check point (operation step S410) at the same time. Whenthe electric potential V_(ppm) is determined to be at the high level(i.e., the first voltage level), the electric potential V_(ppm) isdriven to the low level (i.e., the second voltage level) at time t₁ (thefirst timing) at operation step S415. Both Die 0 and Die 1 then wait forthe respective first delay time period t_(dly_1_Die 0) andt_(dly_1_Die 1) at operation step S420 according to the respective firstPPC routine 400 _(Die_0) and the second PPC routine 400 _(Die_1).

In the example in FIG. 6, the first delay time period t_(dly_1_Die 0) ofDie 0 is shorter than the first delay time period t_(dly_1_Die 1) of Die1. As such, the first PPC routine 400 _(Die_0) for Die 0 completesoperation step S420 before the second PPC routine 400 _(Die_1) for Die1. When it is determined that there is no pausing signal (e.g., thepositive pulse) in the electric potential V_(ppm) at the second checkpoint according to operation step S425 of the first PPC routine 400_(Die_0) for Die 0, the pausing signal is subsequently generated at timet₂ (i.e., the second timing) at operation step S430.

While Die 1 is waiting during the first delay time periodt_(dly_1_Die 1) at operation step S420, the pausing signal is detectedin the electric potential V_(ppm) according to operation step S425 ofthe second PPC routine 400 _(Die_1). In this example, the pausing signaltriggers the second PPC routine 400 _(Die_1) for Die 1 to pause atoperation step S450 after the pausing signal is detected, before thefirst delay time period t_(dly_1_Die 1) can be completed at time t₃ (asshown in FIG. 6).

While the second PPC routine 400 _(Die_1) for Die 1 is paused, the firstPPC routine 400 _(Die_0) for Die 0 continues to operation step S435,i.e., waiting for the second delay time period t_(ppm). Die 0 thenstarts the first PPO at operation step S440 at time t₄. When Die 0completes the first PPO at time t₅, the resuming signal is generatedaccording to operation step S445 of the first PPC routine 400 _(Die_0)for Die 0. In this example, the electric potential V_(ppm) is driven tothe high level.

When the resuming signal is detected according to operation step S455 ofthe second PPC routine 400 _(Die_1) for Die 1, for example, trigged bythe rising edge of the electric potential V_(ppm), the second PPCroutine 400 _(Die_1) resumes and proceeds to operation step S460 bydriving the electric potential V_(ppm) to the low level at time t₆.Next, the second PPC routine 400 _(Die_1) proceeds directly to operationstep S435 because there are only two memory dies in the same PPM group203 and Die 0 has completed the first PPO. After waiting for the seconddelay time period t_(ppm), at time t₇, Die 1 starts the second PPO atoperation step S440. When Die 1 completes the second PPO, the resumingsignal is generated at time t₈ according to operation step S445 of thesecond PPC routine 400 _(Die_1). Here, the electric potential V_(ppm) isdriven to the high level again.

FIG. 7 illustrates yet another exemplary implementation of the PPCroutine 400 shown in FIG. 4, according to some embodiments of thepresent disclosure. In FIG. 7, Die 1 (i.e., the second NAND memory die)receives a command signal for the second PPO after Die 0 (i.e., thefirst NAND memory die) has already completed the second check pointaccording to operation step S425 of the first PPC routine 400 _(Die_0)for Die 0.

In this example, the first PPC routine 400 _(Die_0) for Die 0 starts attime t₁ (i.e., the first timing) at operation step S410, and it isdetermined that the electric potential V_(ppm) is held at the high level(i.e., the first voltage level). Then, the electric potential V_(ppm) isthen driven to the low level (i.e., the second voltage level) accordingto operation step S415. Subsequently, Die 0 waits for the first delaytime period t_(dly_1_Die 0) at operation step S420. Because no pausingsignal (e.g., the positive pulse) is detected in the electric potentialV_(ppm) according to operation step S425, the pausing signal isgenerated at time t₃ (i.e, the second timing) at operation step S430.After the second delay time period t_(ppm)(operation step S435), Die 0starts the first PPO at time t₄ (operation step S440). At time t₅, Die 0completes the first PPO and the resuming signal is generated (operationstep S445). For example, the electric potential V_(ppm) can be driven tothe high level.

In the example in FIG. 7, when Die 1 receives a command signal toperform the second PPO after time t₃, the second PPC routine 400_(Die_1) for Die 1 is started and proceeds to operation step S410. Sincethe electric potential V_(ppm) has been driven to the low levelaccording to the first PPC routine 400 _(Die_0) for Die 0 at time t₃,Die 1 pauses the second PPC routine 400 _(Die_1) at operation step S450.

At time t₅, when the resuming signal is detected according to operationstep S455, the second PPC routine 400 _(Die_1) for Die 1 resumes at timet₆ (operation step S460), where the electric potential V_(ppm) can bedriven to the low level. Here, the resuming of the second PPC routine400 _(Die_1) for Die 1 can be triggered at time t₅ by a rising edge ofthe electric potential V_(ppm). And a falling edge of the electricpotential V_(ppm) at time t₆ results from the electric potential V_(ppm)driven to the low level.

Then, the second PPC routine 400 _(Die_1) for Die 1 proceeds tooperation step S420, where Die 1 waits for the first delay time periodt_(dly_1_Die 1). Die 1 then checks whether there is the pausing signalin the electric potential V_(ppm) at operation step S425. The pausingsignal (i.e., the positive pulse of the electric potential V_(ppm)) isthen generated at time t₇ (i.e., the fourth timing) when it is notdetected. After waiting for the second delay time period t_(ppm)(operation step S435), Die 1 starts the second PPO at operation stepS440. At time t₈, Die 1 completes the second PPO and the resuming signalis generated according to operation step S445 of the second PPC routine400 _(Die_1), for example, by driving the electric potential V_(ppm) tothe high level. As such, Die 0 and Die 1 complete the first PPO and thesecond PPO sequentially.

FIG. 8 illustrates a measurement scheme for a pulse, according to someembodiments of the present disclosure. As an example, a pulse 850 has apulse width t_(pulse). The pulse width t_(pulse) can be a predeterminedvalue, for example, in a range between about 0.1 μS and 10 μS. The pulse850 can be the positive pulse of the electrical potential V_(ppm)described with respect to FIGS. 4-7 and 9-10.

To determine the pulse 850, two measurements can be performed, includinga first probing 852 and a second probing 854. The first probing 852 andthe second probing 854 can be separated with a measurement time periodt_(mea). The measurement time period t_(mea) can be longer than thepulse width t_(pulse) of the pulse 850. For example, the measurementtime period t_(mea) can be about 20 S.

Using the first probing 852 and the second probing 854, the pulse 850can be determine when there is a change in the electric potentialV_(ppm) and both the first probing 852 and the second probing 854 detectthe second voltage level (i.e., the low level) and return a value “0,”for example. In the PPC routine 400 (see FIG. 4), at operation stepS425, if the pausing signal (e.g, the positive pulse) of the electricpotential V_(ppm) is detected when there is a change in the electricpotential V_(ppm) and both the first probing 852 and the second probing854 detect the second voltage level and return the value “0,” the PPCroutine 400 pauses at operation step S450.

On the other hand, if both the first probing 852 and the second probing854 detect the first voltage level (i.e., the high level) and return avalue “1,” e.g., at operation step 410, the electric potential V_(ppm)can be determined to be held at the high level and the PPC routine 400for the memory die can continue to operation steps S415 and S420. If thefirst probing 852 and the second probing 854 obtain different results,e.g., “0” and “1,” then the operation step 410 is repeated until boththe first probing 852 and the second probing 854 measure a highpotential and return the value “1.”

When the first probing 852 detects the low level (returning “0”) and thesecond probing 854 detects the high level (return “1”), it is indicatedthat the rising edge of electric potential V_(ppm) (instead of thepositive pulse) is detected.

FIGS. 9-10 illustrate two exemplary implementations of the PPC routine400 in the PPM system 200B in FIG. 2B, where each PPM group 203 includesthree memory dies (e.g, “Die 0,” “Die 1,” and “Die 2”). Die 0 is alsoreferred to as the first NAND memory die. Die 1 is also referred to asthe second NAND memory die. Die 2 is also referred to as a third NANDmemory die.

In the example shown in FIG. 9, the three memory dies, Die 0, Die 1 andDie 2 of the same PPM group 203 are all at the reset state at thebeginning of the time sequence. Die 0 receives a command signal toperform the first PPO before Die 1 or Die 2. The first PPC routine 400_(Die_0) for Die 0 starts first and proceeds to operation step S410 attime t₁ (the first timing). Because none of the memory dies isperforming PPO, the electric potential V_(ppm) is held at the firstvoltage level (e.g., the high level). As discussed previously, when theelectric potential V_(ppm) is held at the high level, the pull-downcurrent I_(pull_dn) has a magnitude negligible or about the firstcurrent I_(up_1). Namely, all the memory dies (e.g., Die 0, Die 1, andDie 2) in the PPM group 203 are performing operations with the lowcurrent level I_(L). After determining the electric potential V_(ppm) isheld at the first voltage level at time t₁ at operation step S410, theelectric potential V_(ppm) is driven to the second voltage level lowerthan the first voltage level (i.e., the low level) at operation stepS415 according to the first PPC routine 400 _(Die_0) for Die 0.

When Die 1 receives its command signal to perform the second PPO, Die 1starts the operation step S410 of the second PPC routine 400 _(Die_1) attime t₂ (the third timing). Here, time t₂ is later than the time t₁.Since the electric potential V_(ppm) has been driven to the low level byDie 0, the second PPC routine 400 _(Die_1) for Die 1 pauses at operationstep S450. Similarly, when Die 2 receives its command signal to performa third PPO, the electric potential V_(ppm) is detected to be held atthe low level according to operation step S410 of a third PPC routine400 _(Die_2), and subsequently the third PPC routine 400 _(Die_2) forDie 2 is also paused according to operation step S450.

After setting the electric potential V_(ppm) to the low level, Die 0waits for the first delay time period t_(dly_1_Die 0) (operation stepS420). Because no pausing signal (e.g., positive pulse) of the electricpotential V_(ppm) is detected at operation step S425 at time t₃ (thesecond timing), the pausing signal is generated according to operationstep S430 of the first PPC routine 400 _(Die_0) for Die 0. After thesecond delay time period t_(ppm)(operation step S435), Die 0 can startthe first PPO at time t₄ (operation step S440). At time t₅, Die 0completes the first PPO and the resuming signal is generated by, forexample, driving the electric potential V_(ppm) to the high level(operation step S445).

Between time t₂ and time t₅, the second PPC routine 400 _(Die_1) for Die1 and the third PPC routine 400 _(Die_2) for Die 2 are paused atrespective operation steps S450. When the resuming signal is detected attime t₅ (operation step S455), the second PPC routine 400 _(Die_1) forDie 1 and the third PPC routine 400 _(Die_2) for Die 2 can both beresumed. According to the respective operation steps S460 in the secondPPC routine 400 _(Die_1) for Die 1 and the third PPC routine 400_(Die_2) for Die 2, the electric potential V_(ppm) is driven to the lowlevel at time t₆. It is noted that a duration between the rising edgegenerated according to the first PPC routine 400 _(Die_0) for Die 0 attime t₅ and the falling edge generated according to the second PPCroutine 400 _(Die_1) for Die 1 and the third PPC routine 400 _(Die_2)for Die 2 at time t₆ is longer than a pulse width of the positive pulse(i.e., the pausing signal) generated according to the first PPC routine400 _(Die_0) for Die 0 at time t₃. By driving the electric potentialV_(ppm) to the low level, other PPC routines 400 for other memory diesin the same PPM group cannot pass the first check point (at operationstep S410). As such, memory dies (e.g., Die 1 and Die 2) that havepaused at operation step S450 can subsequently complete the second PPOand the third PPO without further delay.

Next, the second PPC routine 400 _(Die_1) for Die 1 and the third PPCroutine 400 _(Die_2) for Die 2 proceed to respective operation stepsS420, where Die 1 waits for the first delay time period t_(dly_1_Die 1)and Die 2 waits for the first delay time period t_(dly_1_Die 2a). Inthis example, the first delay time period t_(dly_1_Die 1) of Die 1 isshorter than the first delay time period t_(dly_1_Die 2a) of Die 2.Accordingly, the second PPC routine 400 _(Die_1) for Die 1 arrives atoperation step S425 before the third PPC routine 400 _(Die_2) for Die 2.When it is determines that there is no pausing signal in the electricpotential V_(ppm), the pausing signal (i.e., positive pulse) isgenerated in the electric potential V_(ppm) at time t₇ (the fourthtiming) according to operation step S430 of the second PPC routine 400_(Die_1) for Die 1.

While the third PPC routine 400 _(Die_2) for Die 2 is waiting for thefirst delay time period t_(dly_1_Die 2a) at the operation step S420, thepausing signal in the electric potential V_(ppm) is detected (operationstep S425). In this example, the pausing signal triggers the third PPCroutine 400 _(Die_2) for Die 2 to pause at operation step S450, beforecompleting the first delay time period t_(dly_1_Die 2a).

While the third PPC routine 400 _(Die_2) for Die 2 is paused, the secondPPC routine 400 _(Die_1) for Die 1 continues to operations step S435.After waiting for the second delay time period t_(ppm) (operation stepS435), Die 1 then starts the second PPO at operation step S440. At timet₈, Die 1 completes the second PPO and the resuming signal is generatedby, for example, driving the electric potential V_(ppm) to the highlevel, according to operation step S445 the second PPC routine 400_(Die_1). By now, Die 0 and Die 1 have completed the first PPO and thesecond PPO, respectively, and the first PPC routine 400 _(Die_0) for Die0 and the second PPC routine 400 _(Die_1) for Die 1 are both completed.

When the resuming signal is detected (e.g., at the rising edge of theelectric potential V_(ppm)) at time t₈ according to operation step S455,the third PPC routine 400 _(Die_2) for Die 2 resumes. At operation stepS460, the electric potential V_(ppm) is driven to the low level toprevent other memory dies in the same PPM group 203 to start the PPO orthe PPC routine 400.

Die 2 then waits for the first delay time period t_(dly_1_Die 2b) atoperation step S420. In this example, the first delay time periodt_(dly_1_Die 2b) is different from the first delay time periodt_(dly_1_Die 2a) because the first delay time periods t_(dly_1_Die 2b)and t_(dly_1_Die 2a) are randomly generated. In some embodiments, thefirst delay time periods t_(dly_1_Die 2b) and t_(dly_1_Die 2a) can bethe same for Die 2 as long as the first delay time period is unique toeach memory die in the same PPM group 203. When it is determined thatthere is no pausing signal in the electric potential V_(ppm), thepausing signal is generated at time t₉ according to operation step S430of the third PPC routine 400 _(Die_2). After waiting for the seconddelay time period t_(ppm)(operation step S435), Die 2 can start thethird PPO at operation step S440. At time t₁₀, Die 2 completes the thirdPPO and the resuming signal is generated by, for example, driving theelectric potential V_(ppm) to the high level (operation step S445).

By using the PPC routine 400, multiple memory dies can coordinate theirPPOs through their PPM circuits 202. By regulating the electricpotential V_(ppm) shared by the PPM contact pads 204 of the PPM circuits202 in the same PPM group 203, PPOs can be de-synchronized for thememory dies.

FIG. 10 illustrates another exemplary implementation of the PPC routine400, according to some embodiments of the present disclosure. In FIG.10, Die 0 (the first NAND memory die), Die 1 (the second NAND memorydie) and Die 2 (the third NAND memory die) receive the command signalsfor the first PPO, the second PPO and the third PPO simultaneously fromthe NAND storage system 10. The first PPC routine 400 _(Die_0), thesecond PPC routine 400 _(Die_1) and the third PPC routine 400 _(Die_2)arrive at the first check point (operation step S410) at the same time.When the electric potential V_(ppm) is determined to be held at thefirst voltage level (i.e., the high level), the electric potentialV_(ppm) is thereby driven to the second voltage level (i.e, the lowlevel) at time t₁ (the first timing) at operation step S415. Die 0, Die1 and Die 2 then wait for the respective first delay time periodt_(dly_1_Die 0), t_(dly_1_Die 1a) and t_(dly_1_Die 2a) at operation stepS420.

In the example in FIG. 10, the first delay time period t_(dly_1_Die 0)for Die 0 is the shortest. As such, Die 0 completes operation step S420before Die 1 or Die 2. When it is determined at time t₂ (the secondtiming) that there is no pausing signal (e.g., the positive pulse) inthe electric potential V_(ppm) at the second check point according tooperation step S425 of the first PPC routine 400 _(Die_0) for Die 0, thepausing signal is generated according to operation step S430.

While Die 1 and Die 2 are performing the operation step S420, i.e.,waiting for the first delay time period t_(dly_1_Die 1a) andt_(dly_1_Die 2a), respectively, both Die 1 and Die 2 detect the pausingsignal in the electric potential V_(ppm) (operation step S425), whichtriggers both Die 1 and Die 2 to start operation step S450 and pause thesecond PPC routine 400 _(Die_1) and the third PPC routine 400 _(Die_2)before completing the first delay time period t_(dly_1_Die 1a) andt_(dly_1_Die 2a), respectively.

While the second PPC routine 400 _(Die_1) for Die 1 and the third PPCroutine 400 _(Die_2) for Die 2 are paused, the first PPC routine 400_(Die_0) for Die 0 continues to operation step S435, where Die 0 waitsfor the second delay time period t_(ppm). Die 0 then starts the firstPPO at operation step S440 at time t₄. When Die 0 completes the firstPPO at time t₅, the resuming signal is generated by, for example,driving the electric potential V_(ppm) to the high level, according tooperation step S445 of the first PPC routine 400 _(Die_0).

When Die 1 and Die 2 detect the resuming signal (e.g., the rising edgeof the electric potential V_(ppm)) at operation step S455, the secondPPC routine 400 _(Die_1) for Die 1 and the third PPC routine 400_(Die_2) for Die 2 resume and proceed to operation step S460, where theelectric potential V_(ppm) is driven to the low level at time t₆. Next,both Die 1 and Die 2 perform the operation step S420, where Die 1 waitsfor the first delay time period t_(dly_1_Die 1b) and Die 2 waits for thefirst delay time period t_(dly_1_Die 2b). In this example, the firstdelay time period is generated randomly as such the first time periodt_(dly_1_Die 1a) and t_(dly_1_Die 1b) are different for Die 1, and thefirst time period t_(dly_1_Die 2a) and t_(dly_1_Die 2b) are differentfor Die 2. In some embodiments, the first delay time periodt_(dly_1_Die 1a) and t_(dly_1_Die 1b) can be the same for Die 1 and thefirst time period t_(dly_1_Die 2a) and t_(dly_1_Die 2b) can be the samefor Die 2. In this example, the first time period t_(dly_1) can bepredetermined by the NAND storage system 10 as long as it is unique foreach memory die.

In the example in FIG. 10, the first delay time period t_(dly_1_Die 1b)for Die 1 is shorter than the first delay time period t_(dly_1_Die 2b)for Die 2. Accordingly, Die 1 starts operation step S425 (i.e., thesecond check point) before Die 2. According to operation step S425 ofthe second PPC routine 400 _(Die_1) for Die 1, it is determined whetherthere is the pausing signal in the electric potential V_(ppm) at time t₇(the fourth timing). When the pausing signal is not detected, thepausing signal of the electric potential V_(ppm) is then generated(operation step S430). Subsequently, the pausing signal generated by Die1 triggers Die 2 to stop operation step S420 and pause the third PPCroutine 400 _(Die_2) at operation step S450.

For Die 1, after waiting for the second delay time period t_(ppm)(operation step S435), Die 1 can start the second PPO at operation stepS440 at time t₈. When Die 1 completes the second PPO, the resumingsignal is generated by, for example, driving the electric potentialV_(ppm) to the high level at time t₉, according to the operation stepS445 of the second PPC routine 400 _(Die_1).

When Die 2 detects the resuming signal generated by Die 1 while pausingat operation step S450, the third PPC routine 400 _(Die_2) for Die 2resumes and proceeds to operation step S460 where the electric potentialV_(ppm) is driven to the low level. Die 2 then perform the operationstep S420 and waits for the first delay time period t_(dly_1_Die 2c).The third PPC routine 400 _(Die_2) for Die 2 continues to operation stepS425 (i.e., the second check point). As discussed previously, Die 2checks for the pausing signal in the electric potential V_(ppm) andgenerates the pausing signal at time t₁₀ when it is not detected(operation step S430). After waiting for the second delay time periodt_(ppm) (operation step S435), Die 2 starts the third PPO at operationstep S440. When Die 2 completes the third PPO, the resuming signal isgenerated by, for example, driving the electric potential V_(ppm) to thehigh level at time t₁₁, according to operation step S445. At this time,all three memory dies Die 0, Die 1 and Die 2 have completed the PPOs oneby one.

In summary, the present disclosure provides a method of peak powermanagement (PPM) for multiple NAND memory dies. The multiple NAND memorydies have a first NAND memory die and a second NAND memory die, and eachof the first NAND memory die and the second NAND memory die includes aPPM circuit having a PPM contact pad held at an electric potentialcommon between the first NAND memory die and the second NAND memory die.The method includes the following steps: detecting the electricpotential of the PPM contact pad at a first timing during a first peakpower check (PPC) routine for the first NAND memory die; driving theelectric potential of the PPM contact pad to a second voltage level ifthe detected electric potential is at a first voltage level at the firsttiming, wherein the second voltage level is lower than the first voltagelevel; enabling the first NAND memory die to wait for a first delay timeperiod; determining whether there is a pausing signal in the electricpotential of the PPM contact pad at a second timing during the first PPCroutine for the first NAND memory die, wherein the second timing islater than the first timing; generating the pausing signal in theelectric potential of the PPM contact pad to pause a second PPC routinefor the second NAND memory die if no pausing signal is detected at thesecond timing; enabling the first NAND memory die to perform a firstpeak power operation; and generating a resuming signal in the electricpotential of the PPM contact pad to resume the second PPC routine forthe second NAND memory die after the first NAND memory die completes thefirst peak power operation.

Another aspect of the present disclosure provides a peak powermanagement (PPM) system for managing peak power operations between twoor more NAND memory dies. The PPM system includes a PPM circuit on eachNAND memory die. Each PPM circuit includes a first pull-up driverelectrically connected to a first power source and a first end of a PPMresistor; a second pull-up driver electrically connected to a secondpower source and a second end of the PPM resistor; a pull-down driverelectrically connected to the second end of the PPM resistor; and a PPMcontact pad connected to the second end of the PPM resistor. The PPMcontact pads of the two or more NAND memory dies are electricallyconnected with each other so that an electric potential of the PPMcontact pads is common between the two or more NAND memory dies. The PPMsystem is configured to manage peak power operations according to theelectric potential of the PPM contact pads.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the present disclosure that others can, byapplying knowledge within the skill of the art, readily modify and/oradapt, for various applications, such specific embodiments, withoutundue experimentation, and without departing from the general concept ofthe present disclosure. Therefore, such adaptations and modificationsare intended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the disclosure and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the disclosure andguidance.

Embodiments of the present disclosure have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections can set forth one or more but not allexemplary embodiments of the present disclosure as contemplated by theinventor(s), and thus, are not intended to limit the present disclosureand the appended claims in any way.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A peak power management (PPM) system for managingpeak power operations between two or more NAND memory dies, comprising:a PPM circuit on each NAND memory die, each PPM circuit comprising: afirst pull-up driver electrically connected to a first power source anda first end of a PPM resistor; a second pull-up driver electricallyconnected to a second power source and a second end of the PPM resistor;a pull-down driver electrically connected to the second end of the PPMresistor; and a PPM contact pad connected to the second end of the PPMresistor, wherein PPM contact pads of the two or more NAND memory diesare electrically connected with each other so that an electric potentialof the PPM contact pads is common between the two or more NAND memorydies, wherein the PPM system is configured to manage peak poweroperations according to the electric potential of the PPM contact pads.2. The PPM system of claim 1, wherein the PPM system further comprises acomparator with a first input terminal electrically connected to the PPMcontact pads of the two or more NAND memory dies and a second inputterminal electrically connected to a reference voltage.
 3. The PPMsystem of claim 2, wherein the electric potential of the PPM contactpads is higher than the reference voltage when the pull-down driver isswitched off.
 4. The PPM system of claim 2, wherein the electricpotential of the PPM contact pads is lower than the reference voltagewhen the pull-down driver is switched on.
 5. The PPM system of claim 1,wherein the two or more NAND memory dies comprise a first NAND memorydie and a second NAND memory die, and the PPM contact pad held at anelectric potential common between the PPM circuit disposed on the firstNAND memory die and the PPM circuit disposed on the second NAND memorydie.
 6. The PPM system of claim 5, wherein the PPM circuit is configuredto: detect the electric potential of the PPM contact pad at a firsttiming during a first peak power check (PPC) routine for the first NANDmemory die; drive the electric potential of the PPM contact pad to asecond voltage level if the detected electric potential is at a firstvoltage level at the first timing, wherein the second voltage level islower than the first voltage level; enable the first NAND memory die towait for a first delay time period; determine whether there is a pausingsignal in the electric potential of the PPM contact pad at a secondtiming during the first PPC routine for the first NAND memory die,wherein the second timing is later than the first timing; generate thepausing signal in the electric potential of the PPM contact pad to pausea second PPC routine for the second NAND memory die if no pausing signalis detected at the second timing; enable the first NAND memory die toperform a first peak power operation; and generate a resuming signal inthe electric potential of the PPM contact pad to resume the second PPCroutine for the second NAND memory die after the first NAND memory diecompletes the first peak power operation.
 7. The PPM system of claim 6,wherein the PPM circuit is further configured to: detect the electricpotential of the PPM contact pad at a third timing during the second PPCroutine for the second NAND memory die.
 8. The PPM system of claim 7,wherein the PPM circuit is further configured to: enable the second NANDmemory die to pause the second PPC routine if the detected electricpotential is at the second voltage level at the third timing.
 9. The PPMsystem of claim 8, wherein the PPM circuit is further configured to:resume the second PPC routine for the second NAND memory die in responseto the resuming signal generated after the first NAND memory diecompletes the first peak power operation.
 10. The PPM system of claim 9,wherein the PPM circuit is further configured to: drive the electricpotential of the PPM contact pad to the second voltage level; and enablethe second NAND memory die to wait for a third delay time period,wherein the third delay time period of the second NAND memory die isdifferent from the first delay time period of the first NAND memory die.11. The PPM system of claim 6, wherein the two or more NAND memory diesfurther comprise a third NAND memory die, wherein the PPM contact pad isheld at an electric potential common between the PPM circuit disposed onthe second NAND memory die and the PPM circuit disposed on the thirdNAND memory die.
 12. The PPM system of claim 11, wherein the PPM circuitis further configured to: determine whether there is the pausing signalin the electric potential of the PPM contact pad at a fourth timingduring the second PPC routine for the second NAND memory die, whereinthe fourth timing is later than the third timing; generate the pausingsignal in the electric potential of the PPM contact pad to pause a thirdPPC routine for the third NAND memory die among the multiple NAND memorydies if no pausing signal is detected at the fourth timing; enable thesecond NAND memory die to perform a second peak power operation; andgenerate the resuming signal in the electric potential of the PPMcontact pad to resume the third PPC routine for the third NAND memorydie after the second NAND memory die completes the second peak poweroperation.
 13. The PPM system of claim 7, wherein the PPM circuit isfurther configured to: enable the second NAND memory die to wait for athird delay time period if the detected electric potential is at thefirst voltage level at the third timing, wherein the third delay timeperiod of the second NAND memory die is different from the first delaytime period of the first NAND memory die.
 14. The PPM system of claim13, wherein the PPM circuit is further configured to: determine whetherthere is the pausing signal in the electric potential of the PPM contactpad at a fourth timing during the second PPC routine for the second NANDmemory die, wherein the fourth timing is later than the third timing.15. The PPM system of claim 14, wherein the PPM circuit is furtherconfigured to: pause the second PPC routine for the second NAND memorydie if the pausing signal is detected at the fourth timing.
 16. The PPMsystem of claim 15, wherein the PPM circuit is further configured to:resume the second PPC routine for the second NAND memory die in responseto the resuming signal generated after the first NAND memory diecompletes the first peak power operation.
 17. The PPM system of claim 1,wherein the first pull-up driver and the second pull-up driver comprisep-channel metal oxide semiconductor field effect transistors (MOSFETs).18. The PPM system of claim 1, wherein the pull-down driver comprises ann-channel metal oxide semiconductor field effect transistor (MOSFET).19. The PPM system of claim 1, wherein the PPM contact pads areelectrically connected through a die-to-die connection, comprising ametal interconnect.
 20. The PPM system of claim 1, wherein the PPMcontact pads are electrically connected through flip-chip bonding,die-to-die bonding, or wire-bonding.